Igniter composition comprising a perchlorate and potassium hexacyano cobaltate iii

ABSTRACT

Energetic and rapid burning compositions suitable for use as a rapid deflagrating material, for ignition of other materials, e.g., hot wire ignition and/or for use in primers and the like, are prepared by dissolving in aqueous solution one or more powerful oxidizer salts such as alkali metal, especially potassium perchlorates, chlorates, chromates, or nitrates, along with a cyano metal complex fuel such as potassium or sodium ferricyanide, ferrocyanide, cobaltocyanide, or closely similar materials, then coprecipitating by pouring the aqueous solution into a water-compatible organic non-solvent liquid such as C2 to C4 monohydric alcohol. Specifically disclosed are compositions of major proportions of potassium perchlorate or dichromate and minor proportions of potassium ferricyanide K3Fe(CN)6, or the analogous cobaltate K3Co(CN)6. The reaction product is precipitated from the water solution by dumping it into an excess of 2-propanol. The precipitation procedure produces a much smoother and more homogeneous product than comparable prior art pyrotechnic materials. The products have a burning velocity which is intermediate between those of conventional pyrotechnic ignition materials and detonating materials such as &#39;&#39;&#39;&#39;Primacord&#39;&#39;&#39;&#39; and similar products.

United States Patent [191 Fronabarger IGNITER COMPOSITION COMPRISING APERCHLORATE AND POTASSIUM HEXACYANO COBALTATE III [75] lnventor: John W.Fronabarger, Phoenix,

Ariz.

[73] Assignee: Unidynamics/Phoenix, Inc.,

Goodyear, Ariz.

22 Filed: Nov. 24, 1972 [21] App]. No.: 308,965

[52] U.S. Cl 149/77, 149/86, 149/109 [51] Int. Cl. C06c 1/00 [58] Fieldof Search 149/45, 46, 61, 75, 76, 77, 149/86, 109

[56] References Cited UNITED STATES PATENTS 97,566 12/1869 Taylor .L149/86 2,995,429 8/1961 Williams et a1. 149/86 X 2,899,468 8/1959 Cadle149/36 X 2,951,335 9/1960 Stengel 149/36 86,980 2/1869 Gomez... 149/77691,919 111902 Stire..'.... 149/86 3,147,160 9/1964 McCrone... 149/763,523,840 8/1970 Bedell 149/36 X 3,673,015 6/1972 Sollott et al. 149/45X OTHER PUBLICATIONS Greene et al., Chem. Abs., 59, No. 10968d (1963) QD1 A51 1 Feb. 19, 1974 Primary Examiner Carl D. Quarforth AssistantExaminer-E. A. Miller Attorney, Agent, or Firm-Cahill, Sutton & Thomas 57 ABSTRACT Energetic and rapid burning compositions suitable for use asa rapid deflagrating material, for ignition of other materials, e.g.,hot wire ignition and/or for use in primers and the like, are preparedby dissolving in aqueous solution one or more powerful oxidizer saltssuch as alkali metal, especially potassium perchlorates, chlorates,chromates, or nitrates, along with a cyano metal complex the] such aspotassium or sodium ferricyanide, ferrocyanide, cobaltocyanide, orclosely similar materials, then coprecipitating by pouring the aqueoussolution into a water-compatible organic non-solvent liquid such as C toC monohydric alcohol. Specifically disclosed are compositions of majorproportions of potassium perchlorate or dichromate and minor proportionsof potassium ferricyanide K Fe(CN) or the analogous cobaltate K Co(CN)The reaction product is precipitated from the water solution by dumpingit into an excess of 2-propanol. The precipitation procedure produces amuch smoother and more homogeneous product than comparable prior artpyrotechnic materials. The products have a burning velocity which isintermediate between those of conventional pyrotechnic ignitionmaterials and detonating materials such as Primacord and similarproducts.

3 Claims, No Drawings IGNITIER COMPOSITION COMPRISING A PERCI-ILORATEAND POTASSIUM HEXACY ANO COBALTATEJII BACKGROUND AND PRIOR ART Numerouscompositions designed for use as explosives, propellants, ignitcrs,elements of pyrotechnics, etc., have been proposed in the past. In manyof these, various chlorates and/or perchlorates especially the alkalimetal and ammonium salts, have been employed as oxidizers. A variety ofcombustible materials have been employed as fuels. Thus, in the old 1864US. Patent to Halvorson, No. 43,021, it is suggested that explosives canbe created by saturating saw dust with Prussian blue or ferricferrocyanide, Fe,,(Fe(CN) and combining the treated saw dust with anoxidizer, such as potassium chlorate, in combination with potassiumnitrate. The saw dust is immersed in a saturated solution of theoxidizer saltsand the latter are precipitated with alcohol to leave adoughy mass which can be used as an explosive. In this patent, ofcourse, thesaw dust is the main fuel. 7 v

In other references, e.g., US. Pat. No. 2,941,352, compositions designedfor use as rocket propellants are compounded by mixing powerful granularor solid oxidizers such as nitrates or perchlorates into rubbery binderswhich also serve as fuels. To control or modify the burning rate, ironcyanide complexes such as Prussian blue, Milori blue, etc. may beincorporated into the rubbery binder before the solid oxidizer materialis mixed in. The ferrocyanide or analogous material, such as cobaltoussalts or chromic, etc., in this case is .in finely particulated form andis used in'proportions of about one part by weight per seven to 200parts of oxidant. Here the rubber is the primary fuel.

Still other compositions described in the prior art are concerned withexplosive compositions made up of KCl plus starch, brick dust and asmall amount of potassium ferrocyanide or similar material to affect thereaction rate, as in US. Pat. No. 1,028,950; analogous matchcompositions and ignition materials for selflighting cigarettes aresuggested respectively in US. Pat. Nos. 1,406,176 and 2,130,115. Asearly asU.S. Pat. No. 97,566, explosives for blasting were suggested tobe made up of a mixture of potassium ferrocyanide, paraffin and chlorateof potash. Later references, such as US. Pat. No. 3,214,308, havesuggested still other combinations including perchlorates andferrocyanides.

In the prior art described, the compositions generally have been made upof a blend of heterogeneous materials, i.e., discrete particles 'orcrystals of the oxidizer salt such as perchlorate, chlorate or nitrate,and separate particles, although often very finely ground, of theferrocyanide or analogous material. Because of their heterogeneousnature, these products have varied in their performance and not beenideal ignition agents or primers.

By contrast, the compositions of the present inven tion are homogeneousmaterials having uniform ignition and burning properties which can becontrolled or modified to meet particular requirements. Also, whereasmost of the prior art compositions are made up mainly of oxidizer andorganic fuel (or in some cases, a high energy combustiblemetal), in thepresent case the composition consists essentially of the two salts,coprecipitated from a common solution to produce a highly homogeneousproduct. That is, the cyano complexes serve as primary fuels.

DESCRIPTION OF PREFERRED EMBODIMENT The products of the presentinvention are compositions of high energy which are particularlysuitable as ignition materials, especially for use in metal claddeflagrating cord and also for hot wire ignition and/or for use inpriming devices. They are energetic and moderately rapid burning but donot detonate. They are safe to handle, being relatively inert to impact.

The oxidizers may be'any of the following or combinations or any two ormore thereof, in various proportions, as will be understood by thoseskilled in the art:

a. metal, ammonium and amine perchlorates;

b. metal, ammonium and amine chlorates;

c. metal, ammonium and amine nitrates;

(1. metal, ammonium and amine hexanitro-cobaltates (III),cobaltinitrites, e.g., K Co(NO H 0 and equivalent homologs andderivatives of any of these.

1 e. metal, ammonium or amine dichromates;

f. metal permanganates. The fuels, on the other hand,-may. be selectedfrom any oneor more of the following materials:

a. metal hexacyanocobaltates III (cobalticyanides),

e.g., K Co(CN) b. metal hexacyanoferrates III (typically ferricya-.nides, e.g., K Fe(CN) or hexacyanoferrates Il (ferrocyanides l(.,Fe(CN)3H O);

c. metal hexacyanomanganates Ill; and

d. cyano complexes of nickel and chromium.

These compositions are prepared by dissolving together appropriateproportions of the oxidizers and fuelsiin a cosolvent and thencoprecipitating by pouring the resulting'solution into anorganic liquidin which the salts are not soluble. Water is a suitable cosolventfor-most of the materials listed above and a watercompatible alcohol, inwhich all the salts are quite insoluble, is preferred forcoprecipitation. For the latter purpose, a C to C a]cohol, i.e., ethyl,propyl or butyl alcohol may be used, the propyl alcohols such as 2-propanol being generally preferred because of good water compatibilitycombined with very low solvency for the salts and fuels. In some cases,low molecular weight ketones maybe used inlieu of or in combination withone or more of the alcohols just mentioned.

The coprecipitated products are homogeneous and smooth and uniform, ascompared to the conventional mechanically blended compositions commonlymade for pyrotechnic purposes. They are referred to hereinafter asreaction products, although in some cases they may be mere mixtures.

The ratios of oxidizer to fuel may be altered within rather wide limitsto provide latitude and variation in properties and performance. Ingeneral, one to five parts by weight of the oxidizer will be used withtwo to one parts-by weight of the fuel compound. Usually, the oxidizerequals or exceeds the other component in weight, preferable limits beingone to three parts of oxidizer to one part of fuel. The ratio of fuel tooxidizer is adjusted to obtain the desired oxidant balance.

The products of this process are useful as priming compositionsparticularly in the form of metal clad deflagrating cord, but also inelectric and fuse type caps and in suitable form for hot wire ignition.They are reliably ignitable but are not unduly sensitive, beinggenerally less susceptible to impact than conventional basic leadstyphnate, for example, under similar conditions. Most of them are hotwire sensitive and very rapid burning, as compared to most pyrotechniccompositions, but they are not of detonating velocity.

EXAMPLE 1 A composition was made up by first dissolving 61 parts byweight of potassium perchlorate, 'KC10 and 39 parts of potassiumferricyanide, K Fe(CN) in warm water and then precipitating by pouringthe solution into an excess of Z-propanol. The homogeneous precipitatewhich formed was allowed to dry and thereafter was tested for itsignition properties. It was found to be ignitable by a l-ohm wire (alength of 0.005 inch of nichrome wire having resistance of 158 ohms perfoot) at a current of 1.5 amperes. It was also ignitable from a 100microfarad capacitor charged at 10 volts through a S-ohm wire. Using al-ohm bridge and a current of 2 amperes or more, the ignition times wereslightly slower but still comparable to times for conventional basiclead styphnate (BLS) when used under comparable conditions.

This material also exhibited a no-fire energy from a l-ohm wire whichwas greater than that shown by BLS and it was found to be less sensitiveto impact, and hence, safer to handle, than BLS.

EXAMPLE 2 A composition was made up in the same manner as in Example 1but consisted of 61 parts by weight of potassium perchlorate and 39parts of potassium hexacyanocobaltate (cobalticyanide, K Co(CN) This wasprecipitated in propyl alcohol as in Example 1 and allowed to dry beforetesting.

The product was found to be ignitable from a l-ohm wire, as above, at 2amperes. At higher current, 3 amperes or more, the ignition times wereslightly slower but comparable to those obtained with basic leadstyphnate (BLS), as in Example 1, above. Here again, the compositionshowed a no-fire energy from a l-ohm wire which was greater than thatobtained from BLS. The composition of Example 2 was found to have aballistic potential approximately equal to that produced by normal leadstyphnate. As in the case of Example 1, this composition was also lesssensitive to impact than basic lead styphnate.

The product of Example 1 was formed into a drawn aluminum-sheath cord of0.093 inch outside diameter, containing 3.7 grams of ignition materialper running foot. Samples of this metal sheathed cord 6 inches long wereignited with a 7 milligram cc ignition element to test the burning rate.Seven such samples showed burning rates as indicated below. An eighthsample was ignited with a Hercules D3A2 detonator:

Test No. Burning rate, in/sec.

Depending on compaction or density, the burning velocity can be variedfrom about 4,000 to 1,200 inches per second.

EXAMPLE 3 A composition was made up in the same manner as in Example 1,but consisted of 82 parts by weight of potassium dichromate and 18 partsof potassium ferricyanide. These were dissolved in water and thereaction product precipitated in isopropyl alcohol as in Example 1. Theprecipitate was allowed to dry before testing.

This product was easily ignitable by flame. However, it burned rapidlybut without a flash or report, as compared to the more active materialsof Examples 1 and 2. This product appears to have utility inapplications where softer ignition characteristics are desirable.

In this particular composition, proportions may be varied between about60 to parts by weight of the oxidizer salt and 10 to 40 parts of themetal complex fuel salt.

It was found on further tests that the products described above, inExamples 1, 2 and 3, were superior in thermal stability to basic leadstyphnate. It appears that many of the products of this invention willhave superior thermal stability.

The combination of oxidizer salt and fuel complex, without organic orother fuel constituents, normally is preferred. However, as suggestedabove, the compositions of this invention can be varied in energy,stability, sensitivity, and in other respects, by varying theingredients used and the proportions of each, as will be readilyunderstood by those skilled in the art. It will be obvious, also, thatvarious conventional additives and modifiers may be incorporated tofurther control sensitivity and energy characteristics.

Conventional and available fuel binders may be used. For example,polybutadiene and/or polybutadieneacrylic acid copolymers, copolymers ofpolybutadiene and acrylonitrile, polyvinylidene compositions andcopolymers such as those of polyvinylidene fluoride andperfluoropropylene, and other and analogous halogenated polymers may beused, singly or in various combinations.

Inert fillers, such as kieselguhr, as well as powdered, particulate orfibrous materials which may have fuel value, such as starches, sugars,cabonaceous fines, such as ground charcoal, coal, gilsonite, etc., maybe added to dilute or to increase energy, etc. as will be understood bythose skilled in the art. Moisture absorbents or dessicants of varioustypes may be used to offset high atmospheric humidity in appropriatecases, as also will be self-evident to those familiar with the art.

It is intended by the foregoing and by the claims which follow, to coverthe various modifications and variations described above and otherswhich will suggest themselves to those skilled in the art, as far as thestate of the prior art properly permits.

What is claimed is:

I. An energetic and rapid burning composition comprising one to fiveparts by weight of an oxidizer salt selected from the group whichconsists of alkali metal and ammonium perchlorates and two to one partsby weight of potassium hexacyano cobaltate lll.

2. A composition according to claim 1 in which the weight ratios arebetween one and three parts of oxidizer salt to one part of fuel.

3. A composition according to claim 1 in which the oxidizer salt ispotassium perchlorate and the fuel is potassium hexacyanocobaltate.

2. A composition according to claim 1 in which the weight ratios arebetween one and three parts of oxidizer salt to one part of fuel.
 3. Acomposition according to claim 1 in which the oxidizer salt is potassiumperchlorate and the fuel is potassium hexacyanocobaltate.